Methods and apparatus for making sacks or bags

ABSTRACT

A method and apparatus for making bags or sacks which comprise an outer sack and an inner sack, part of which projects from the mouth end of the outer sack. Tube portions for the inner sacks are applied to a web of material for the outer sack, and the web is made into a tube around the tube portions and divided into the lengths required for the individual sacks. The sacks pass through the apparatus with their mouth end leading, the mouth end of each inner sack being folded inwardly by the amount corresponding to the intended projecting part of the inner sack. The apparatus has a double-belt conveyor for passing the inner sack tube portions over a displaceable plate which initiates the inward fold and which then pushes the folded edge into a second double-belt conveyor to complete the fold and convey the tube portion on to the outer sack web.

Unite States atent [191 Winnemoller Jan. 8, 1974 [75] Inventor: my; Winnem01ler,Rhme, Germany [73] Assignee: Windmoller & Holscher, Lengerich,

Westphalia, Germany [22] Filed: Feb. 29, 1972 [21 Appl. No.: 230,360

[30] Foreign Application Priority Data Mar. 6, 1971 Germany P 21 10 815.6

[52] US. Cl. 93/35 1R, 93/8 W, 93/18, 156/519 ['51] lll'lt. C1 13311) 39/02 [58] Field of Search 93/19, 35 R, 8 W, 93/8 R, 18, 36.01; 156/519, 522;225/100, 106

[56] References Cited UNITED STATES PATENTS 2,803,173 8/1957 Doyle 93/19 3,664,238 5/1972 Baxter et a1. 156/521 X 2,259,752 10/1941 Kimple i 93/35 R 3,391,615 7/1968 Lepisto 93/35 R X 2,054,298 9/1936 Poppe 93/35 R 6/1966 Becker 93/35 R 11/1938 Boehmer 93/35 R Primary Examiner-Andrew R. Juhasz Assistant ExaminerJames F. Coan Att0rneyMartin Fleit et a1.

[57] ABSTRACT A method and apparatus for making bags or sacks which comprise an outer sack and an inner sack, part of which projects from the mouth end of the outer sack. Tube portions for the inner sacks are applied to a web of material for the outer sack, and the web is made into a tube around the tube portions and divided into the lengths required for the individual sacks. The sacks pass through the apparatus with their mouth end leading, the mouth end of each inner sack being folded inwardly by the amount corresponding to the intended projecting part of the inner sack. The apparatus has a double-belt conveyor for passing the inner sack tube portions over a displaceable plate which initiates the inward fold and which then pushes the folded edge into a second double-belt conveyor to complete the fold and convey the tube portion on to the outer sack web.

11 Claims, 8 Drawing Figures PAINTED- 5 I974.

SHEU 1 (If 4 METHODS AND APPARATUS FOR MAKING SACKS OR lBAGS This invention relates to methods and apparatus for making sacks or bags, comprising an outer sack, preferably made of one or more plies of paper, and an insert or liner sack fitting therein, preferably comprising plastic films, which projects out of the outer sack for filling and closing.

It has been proposed (in UK patent No. 1,253,292) that to produce such sacks or bags, the web of material for the outer sack is divided by transverse perforations into given sack lengths which are still attached to each other, while portions of a length corresponding to the length of the insert sack are cut in per se known manner from a tubular web of insert sack material, and moved one over the other relative to each other in the direction of conveyance of the web, so that they overlap each other by the amount by which the insert sack is to project out of the outer sack. The overlapping portions of the insert sacks are then secured by dots of adhesive to the web of outer sack material so that the leading edges of the insert sack portions lie approximately flush with the transverse perforations in the outer sack material. Finally, the web of outer sack material is made into a tubular shape, thus surrounding the insert sack portions stuck thereto, and singled off into tube portions by tearing the transverse perforations.

For the purpose of tearing the transverse perforations, the insert sack which is stuck in the tube formed by the web of outer sack material participates in the movement of the outer sack tube portion as it is torn off, and slips without restriction out of its position of overlap with the following insert sack. The insert sack therefore projects out of the outer sack tubular portion, by the amount of overlap at the trailing end thereof, the trailing end forming the mouth of the bag or sack. After closing the aligned leading ends of the outer and insert sacks, the sack is sealed ready for use by a transverse seam or a bottom fold.

In sacks produced in accordance with'this method however, the opening end of the insert sack which projects out of the outer sack is exposed to damage and soiling during storage and during transportation of the empty sacks to the consumer, and this can impair satisfactory closing of the inner sacks and often gives rise to unacceptable fouling of the material, for example foodstuffs, to be contained in the sacks.

Apparatus has also been proposed for carryingout the above method, which comprises-first per se known means for forming single-ply or multi-ply tubes for the outer sacks, and second per se known means for advancing and transversely cutting a simple flat or tubular web of material for the insert sacks, wherein associated with the first means, in front of the associated tubeforming apparatus in the direction of conveyance, are a per se known transverse perforating apparatus and a glueing mechanism for applying dots of glue to the-single-ply or multi-ply web of outer sack material, and after the said tube-forming apparatus, a per se known tearing-off apparatus; arranged downstream of the second means are an apparatus for overlapping the portions which are cut off from the simple flat or tubular web of material for the insert sacks, and a conveyor means which moves at the speed of conveyance of the web of outer sack material and which lays the overlapped portions of insert sack material onto the web of outer sack material, the arrangement of the conveyor means being such that the portions of insert sack material are laid onto the web of outer sack material along the section of the latter which extends between the transverse perforating apparatus or the glueing mechanism and the tube-forming apparatus.

It has also already been proposed (U.S. Pat. specification No. 2,803,173) that, when manufacturing multiply sacks with a separate insert sack, a tubular web of material for forming the inner sacks should be laid with an overlapping fold onto aflat web of material for forming the outer sacks, before the web of material is made into tubular shape, and that the web which is made into a tubular shape to produce the finished sack should be singled off with a common cut. In this method the projecting end of the inner sack is folded into the interior of the outer sack, but the cut edge of the inner sack lies flush with the web forming the outer sack, due to the common cut for separating the two webs for forming the inner and outer sacks. As a result, the inside wall of the insert sack is still exposed to the possibility of dirt and is in any case not suitable for the hygienic filling of materials.

In accordance with the invention therefore, for reliably avoiding fouling of the filling end of the inner sack, it is proposed that the tubular sack portions should be formed with the filling end leading, and that the insert sack portions should be folded over through at their leading end by the amount of overlap and then secured by means of dots of adhesive at their trailing end to the web of outer sack material so that the fold edge of the inner sack portion, which is formed by folding over the overlap region, is approximately flush with the transverse perforation in the web of outer sack material.

According to the present invention, there is provided a method of making a sack or bag comprising a singleply or multi-ply outer sack, preferably of paper, and an insert sack, preferably of plastics film, which projects out of the outer sack at the filling end for filling, wherein a web of material comprising one or more transversely displaced plies for the outer sack is moved continuously at a given speed, and the insert sack material of a conveyor length corresponding to the insert sack length is advanced more rapidly approximately by the amount intended in the finished sack to project out of the outer sack, and applied to the web of outer sack material, wherein the web of outer sack material is divided by transverse perforations into given outer sack lengths which are still attached to each other, while portions corresponding to the insert sack length are cut off from the web of insert sack material and attached at one end by means of glue to the web of outer sack material in such a way that said cut edges are flush with the transverse perforations or are at a given spacing therefrom, whereupon the web of outer sack material is made into a tubular shape, thereby surrounding the insert sack portions secured thereto, and singled off into tube portions by tearing the transverse perforations, which tube portions are delivered to a bottommaking or bottom-closing machine, wherein the sack tube portions are formed with the sack filling end leading and the insert sack portions are folded over through 180 at their leading end by the amount intended in the finished sack to project out of the outer sack, and subsequently secured at their trailing end by means of adhesive to the web of outer sack material so that the fold edge of the insert sack portion, which fold edge is formed by said folding-over step, is substantially flush with the transverse perforations in the web of outer sack material.

This method produces sacks in which the insert sacks terminate with a fold edge at the filling or mouth end of the outer sack. The inwardly projecting filling end of the inner sack is in that way reliably protected by the outer sack from fouling and damage. It must obviously be pulled out of the outer sack for filling purposes.

The invention also provides apparatus for carrying out the method according to the invention, comprising first means for forming single-ply or multi-ply tubes for the outer sacks; second means for advancing and transversely cutting a simple flat or tubular web of material for the insert sacks; a tube-forming apparatus for forming the webs of the outer and insert sacks into a tube; a transverse perforating apparatus arranged upstream of the tube-forrning apparatus, for transversely perforating said outer sack web; a glueing mechanism for applying glue to said outer sack web, arranged upstream of the tube-forming apparatus; a tearing-off apparatus arranged downstream of said tube-forming apparatus; an apparatus arranged downstream of said second means for feeding the portions which are cut off from the simple flat or tubular web of material for the insert sacks; and a conveyor means which in operation moves at the speed of conveyance of said outer sack web and which lays the portions of insert sack material onto the the outer sack web, the arrangement of the conveyor means being such that the portions of insert sack material are laid onto the web of outer sack material along the section of the latter which extends between said transverse perforating apparatus or glueing mechanism and said tube-forming apparatus; wherein a double-belt conveyor comprising an upper conveyor belt and a lower conveyor belt is disposed between said second means and said conveyor means, which double-belt conveyor in operation moves at a higher speed than the conveyor means, and wherein at least one belt roller of the pair of belt rollers at the end of the double-belt conveyor at which said insert sack portions are transferred to the conveyor means is reciprocatable in the direction of conveyance of the portions of insert sack material in the rhythm of the machine, with tensioning roilers engaging the outer run for maintaining the tension in the belt, and wherein a folding plate means is provided which is also reciprocatable and which in the foremost position extends with its folding edge into the entry nip of said conveyor means, along a transverse line lying in the region of the leading end, for introducing an insert sack portion into the converging entry nip of said conveyor means, and prematurely releasing the trailing end.

The folding plate permits the insert sack portion which comes out of the doublebelt conveyor at a higher speed to tip downwardly at the forward end thereof over its folding edge, and, folding the downwardly tipped end over, threads it into the following intermediate conveyor which is preferably in the form of a double-belt conveyor and which grips the insert sack portion at its tilted edge, and completes the fold initiated by the folding plate.

In-a further embodiment of the invention, the folding plate is arranged on the lower beltof the double-belt conveyor so as to be movable downwardly from its upwardly directed working position into an inoperative position. In this way, in a simple manner, it is possible, with the folding plate lowered, to use the apparatus as required also to manufacture sacks with the insert sack still projecting out of the outer sack.

In order to ensure that the insert sack tubular portion reliably slides onto the folding plate, in a further aspect of the above apparatus it is provided that the folding plate is of a comb-like construction and is secured at a position lying in the interior of the surface enclosed by the lower conveyor belt of the reciprocating doublebelt conveyor, and, with its fingers projecting between the individual strands of the conveyor belt which is in the form of a strand belt, engages beyond the front reciprocating belt roller.

In order to ensure even better insertion of the end of the insert sack tube, which end hangs over the comblike folding plate, into the entry nip of the intermediate conveyor, the comb-like folding plate is advantageously pivotally connected at its rearward edge to an operating linkage by way of which movement in the direction of conveyance is imparted thereto in the rhythm of the reciprocating movement of the reciprocating belt roller. The operating linkage can comprise a double lever which is pivotally connected with its one end to a respective side of the comb-like folding plate and which is moved by spring force into the retracted rest position of the folding plate and which is pivotally mounted with its pivot centre point in a bearing which is moved with the reciprocating belt roller. The other half of the double lever tenninates freely, and in the path of movement of the free half of the lever, in the region of the forward end of the reciprocating movement, is arranged an adjustable stop which, in conjunction with the forward movement of the pivot centre point of the double lever until the one stroke movement of the reciprocating motion is completely terminated, moves the double lever and thus the comb-like folding plate in the direction of movement of the reciprocating belt roller, overtaking the latter, into the forward working position in opposition to the spring force.

Reliable gripping of the front end, which is still loosely folded over, of the insert sack tube portion, can additionally also be achieved in that the upper belt of the intermediate conveyor which is in the form of a double-belt conveyor is guided in the region of the entry end by means of two guide rollers such that a wedge-shaped entry nip is produced, and that on the inside of the run (nip run) spanning overthe entry nip there is arranged a further roller which is movable transversely to the nip run and which is pressed into and removed again from the nip run in the working rhythm of the machine, whereby the nip is opened and closed in the rhythm of the machine. A similar'effect can also be achieved automatically by the upper belt of the intermediate conveyor, which is in the form of a double-belt conveyor, being passed in the region of the entry end over two guide rollers such as to produce a wedge-shaped intake nip, and by the guide roller which is closest to the conveyor section formed jointly with the lower belt, being resiliently flexibly pressed inwardly into the two upper belt runs which adjoin it.

In order constantly to provide a guiding action for the insert sack portion, at least from above, when forming the fold-over, in an above described apparatus in which the upper belts of the reciprocating double-belt conveyor and the intermediate conveyor are in the form of strand belts, the strands of both upper belts can be ing to the present invention, will now be described byway of example with reference to the accompanying drawings in which:

FIG. 1 shows a diagrammatic side view of an embodiment of the apparatus,

FIG. 2 shows a plan view of the operation of joining a web of outer sack material toinsert sack portions in the apparatus shown in FIG. ll,

FIGS. 3 and 4 show two characteristic phases of the apparatus of FIG. 1, during the operation of folding over the leading end of an insert sack portion,

FIG. 5 shows a side view of another embodiment of the folding mechanism of the apparatus of FIG. 1,

FIG. 6 shows a plan view of the apparatus of FIG. 5,

FIG. 7 shows another embodiment of the pressure roller at the entry end of the intermediate conveyor, for completing the step of folding over the leading end of an insert sack portion, 7

FIG. 8 shows a further plan view of the apparatus of FIG. 5.

The'apparatus shown in FIG. 1 comprises a tube- I forming apparatus 6 for a web A of outer sack material which is continuously advanced in the direction of conveyance a by the pair of feed rollers 1. Arranged upstream of the apparatus 6 are per se known glueing mechanisms (not shown) for applying glue for the adhesive seams of the tube for forming the outer sacks, a transverse perforating apparatus 2 for producing transverse perforations 3, and a glueing mechanism 4 for applying dots of adhesive 5 to the web A of material. Arranged downstream of the apparatus 6 is a tearing-off apparatus 7 which tears outer sack tube portions AS individually from the web A along the transverse perforations 3'. The apparatus of FIG. ll also has a pair of feed rollers 8 associated with a transverse cutting means 9 for feeding a tubular web E of insert sack material and for cutting off insert sack portions ES respectively, an apparatus 10 for mutual overlapping of the insert sack portions ES, and an intermediate conveyor 11, 11' which lays the insert sack portions ES onto the web A, maintaining the overlapping thereof, in synchronism with the web A.

ble-belt conveyor 14 and 17 which advances the insert sack portions ES at a higher speed than the speed of conveyance of the intermediate conveyor 11 and 11' and transfers the portions ES to the conveyor 11 and 11' and in this way produces the mutual overlapping of the insert sack portions ES, the magnitude of the overlap being made equal to the amount by which the insert sack is intended to project out of the outer sack for the purpose of filling and closing thereof, by virtue of the selected difference in speed between the double-belt conveyor 14 and Hand the intermediate conveyor 11 and l 1.

As shown, the intermediate conveyor 11 and 111' is preferably in the form of a double-belt conveyor. Its top belt 11' comprises a plurality of individual parallel bands and at its entry end (towards the left in FIG. 1) it has two guide drums 35 and 36 for the individual bands. Of the two drums 35 and 3.6, the entry end drum 35 is spaced by a distance y from the plane EE of conveyance of the intermediate conveyor 11 and 11', thus producing a wedge-shaped entry or nip 37 to the conveyor. Arranged between the two drums 35 and 36, inthe region of the individual bands which pass over the drum 35, is a pressure roller 38 which is reciprocal relative to the lower belt III in the working rhythm of the apparatus, and which presses the individual bands downwardly towards the lower belt 11 for the purpose of gripping inster sackportions ES inserted into the entry 37. Instead of the pressure roller 38, which is reciprocal relative to the lower belt 11 in the working rhythm of the machine, it is also possible, as shown in FIG. 7, to provide a pressure roller 38 which is springloaded by a spring 42 against the lower belt 11.

The upper belt 14 of the double-belt conveyor 14 and 17 is stationarily mounted. It also comprises a plurality of parallel individual bands and passes at one end (towards the right in FIG. 1) over the same guide drum 35 as the top belt 11' of the intermediate conveyor Ill and 11'. As the double-belt conveyor 14 and 17 moves at a higher speed than the intermediate conveyor 11 and 111', freely rotatable loose pulleys are provided for the individual bands of the upper belt 14, between the guide pulleys which are secured on the shaft 35' of the drum 35 for the individual bands 11'.

The lower individual belt 17 of the double-belt conveyor has its front guide drum 16 reciprocally movable in the working rhythm of the apparatus in the direction indicated by the arrows b-b relative to the wedgeshaped entry 37 into the intermediate conveyor 1 1 and 11', so that each insert sack portion ES is threaded with its leading end into the intermediate conveyor 11 and 11'. A folding plate 39 which projects substantially in the direction of movement of the reciprocatable belt 17 is secured as shown at the discharge end thereof such that towards the end of the forward movement of the drum 16, the front folding edge of the plate 39 extends into the gripping region, that is to say, into the wedgeshaped entry 37 into the intermediate conveyor Ill and 111'. The folding plate 39 is vertically movable and can be fixed in any desired position, by means of a holder 41 which is pivotal about the shaft 40 of the reciprocal guide drum 16 of the conveyor belt 17. The plate 39 can therefore be set either in the working position as described above and as shownin solid lines, or in a downward position as indicated in broken lines in FIG.

1, in which it has no action on the insert sack portions taining the overlap. When the outer sack tube portions are torn off from the web A of material, tube portions AS, ES are thus produced, from which each insert sack portion ES projects rearwardly (relative to the direction of its movement) by the amount of the overlap.

With the folding plate 39 in the working position, each insert sack portion ES which is advanced by the double-belt conveyor 14 and 17 passes over the folding plate39 and, as shown in FIG. 1, is tipped downwardly under the force of gravity over the front edge of the plate 39. As shown in FIG. 3, the portion ES passes into the wedge-shaped entry 37 to the intermediate conveyor l1 and 11 with its downwardly tipped end about the folding plate 39 and, by downward movement of the pressure roller 38 against the fold edge pre-formed by the folding plate 39, is gripped by the intermediate conveyor 11 and 11' which, as shown in FIG. 4, completes the folding operation, pulls the insert sack portion from the folding plate 39 which is again moving back (towards the left of FIGS. 1 and 4), and passes it to the web A. By adjusting the speed of conveyance of the double-belt conveyor 14 and 17, the width x of the folds produced in this way in the sack portions ES can be made equal to the length by which each insert sack is intended to project with its filling end out of the outer sack, for the purposes of filling and closing the sack.

As shown in FIG. 2, the insert sack portion BS is taken from the intermediate conveyor 11 and 11' and laid, with its folded-over edge leading, onto the web A in such a way that the leading edge is flush with the transverse perforations 3 in the web A. After the web A has been formed into a tubular shape in the tubeforming apparatus 6, and after the outer sack tube portion AS has been torn off by means of the tearing apparatus 7, there are produced tubular portions AS-ES in which the insert sack portions are completely enclosed at their folded-over filling end x by the outer sack tube portion. The folded-over end x thus closes the insert sack and is protected from dirt and damage in the interior of the outer sack itself.

FIGS. 5 and 6 show another embodiment of the folding mechanism. The lower individual conveyor belt 17 of the double-belt conveyor 14 and 17, which is reciprocal relative to the intermediate conveyor 11 and 11', comprises a plurality of spaced individual bands 17'. At the discharge end of the conveyor 17 and between the bands 17 thereof, are provided a plurality of folding fingers 43 so arranged that their forward, folding edges are reciprocatable beyond the front guide rollers 44 of the lower belt 17. For this purpose, the fingers 43 are pivotally mounted with their rearward end on a common cross member 45 and lie on the shaft 46 of the rollers 44. The member 45 is supported by means of lateral, double-armed pivotal levers 47 on the frame of the conveyor belt 17. Springs 48 and stops 49 hold the member 45 in a rest position relative to the rollers 44, such that the folding fingers 43 do not project beyond the periphery thereof. Provided in the range of movement of the free lever arms of the pivotal levers 47 are stationary stops 50 against which the lever arms can abut towards the end of the forward movement of the assembly of the rollers 44 of the conveyor belt 17. The stops 50 can be moved as described out of the path of movement of the levers 47, for example by a downward pivotal movement in the direction of the arrow c.

During the forward movement of-the conveyor belt 17 in the direction of the arrow b, the fingers 43 firstly remain in their rest position under the action of the springs 48, so that an insert sack portion ES which is being advanced by the double-belt conveyor 14 and 17 can tip downwardly with its leading edge without friction over the rollers 44. Only towards the end of the portion into the intermediate conveyor 11 and 11, at the same time folding over its front end, as shown in FIG. 5.

By virtue of a downward pivotal movement of the stops in the direction of the arrow 0, the folding fingers 43 can be caused to remain in their rest position under the influence of the springs 48. The apparatus can then operate in the same manner as the apparatus as described above with reference to FIGS. 1 to 4, when the folding plate 39 is moved into its downward inoperative position.

FIG. 8 shows a similar view to that of FIG. 6, with the difference that a bar 43" is provided at the forward ends of the fingers 44 to form a folding plate 43 of comb-like or ladder-like configuration. The insert sack portions are engaged by the bar 43" over its entire width, as in the case of a closed folding plate, and inserted into the entry nip 37 of the double-belt conveyor 11 and 11, which then rolls the transverse fold. The bar 43" thus avoids any danger of damage to the insert sack tube portions by the tips of the fingers 43.

I claim 1. A method of making a sack or bag comprising a single-ply or multi-ply outer sack, preferably of paper, and an insert sack, preferably of plastics film, which projects out of the outer sack at the filling end for filling, wherein a web of material comprising one or more transversely displaced plies for the outer sack is moved continuously at a given speed, and the insert sack material of a conveyor length corresponding to the insert sack length is advanced more rapidly approximately by the amount intended in the finished sack to project out of the outer sack, and applied to the web of outer sack material, wherein the web of outer sack material is divided by transverse perforations into given outer sack lengths which are still attached to each other, while portions corresponding to the insert sack length are cut off from the web of insert sack material, and attached at one end by means of glue to the web of outer sack material in such a way that said cut edges are flush with the transverse perforations or are at a given spacing therefrom, whereupon the web of outer sack material is made into a tubular shape, thereby surrounding the insert sack portions secured thereto, and singled off into tube portions by tearing the transverse perforations, which tube portions are delivered to a bottommaking or bottom-closing machine, wherein the sack tube portions are formed with the sack filling end leading and the insert sack portions are folded over through 180 at their leading end by the amount intended in the finished sack to project out of the outer sack, and subsequently secured at their trailing end by means of adhesive to the web of outer sack material so that the fold edge of the insert sack portion,- which fold edge isforrned by said folding-over step, is substantially flush forward movement of the conveyor belt 17 do the free arms of the levers 47 abut against'the stops 50, with the result that the pivotal folding fingers 43 quickly move sack material.

2. Apparatus comprising first means for forming single-ply or multi-ply tubes for the outer sacks; second means for advancing and transversely cuttinga simple flat or tubular web of material for the insert sacks; a tube-forming apparatus for forming the webs of the outer and insert sacks into a tube; a transverse perforating apparatus arranged upstream of the tube-forming apparatus, for transversely perforating said outer sack web; a glueing mechanism for applying glue to said outer sack'web, arranged upstream of the tube-forming apparatus; a tearing-off apparatus arranged downstream of said tube-forming apparatus; an apparatus arranged downstream of said second means for feeding the portions which are cut off from the simple flat or tubular web of material for the insert sacks; and a conveyor means which in operation moves at the speed of conveyance of said outer sack web and which lays the portions of insert sack material onto the outer sack web, the arrangement of the conveyor means being such that the portions of insert sack material are laid onto the web of outer sack material along the section of the latter which extends between said transverse perforating apparatus or glueing mechanism and said tubeforming apparatus; wherein a double-belt conveyor comprising an upper conveyor belt and a lower conveyor belt is disposed between said second means and said conveyor means, which double-belt conveyor in operation moves at a higher speed than the conveyor means, and wherein at least one belt roller of the pair of belt rollers at the end of the double-belt conveyor at which said insert sack portions are transferred to the conveyor means is reciprocatable in the direction of conveyance of the portions of insert sack material in the rhythm of the machine, with tensioning rollers engaging the outer run for maintaining the tension in the belt, and wherein a folding plate means is provided which is also reciprocatable and which in the foremost position extends with its folding edge into the entry nip of said conveyor means along a transverse line lying in the region of the leading end, for introducing an insert sack portion into the converging entry nip of said conveyor means, and prematurely releasing the trailing end.

3. Apparatus according to claim 2 wherein the folding plate means comprises a folding plate supported on the lower belt of the double-belt conveyor so as to be movable between an upwardly directed working position and a downward inoperative position.

4. Apparatus according to claim 2 wherein the lower conveyor belt of the double-belt conveyor comprises a plurality of stands and the folding plate means comprises a folding plate of a comb-like construction supported at a position lying in the interior of the space enclosed by the lower conveyor belt of the double-belt conveyor, the comb-like fingers projecting between the individual strands of the conveyor belt and being movable to a position in which they extend beyond the reciprocatable belt roller.

5. Apparatus according to claim 4 wherein the comblike folding plate is pivotally connected at its rearward end to an actuating linkage by way of which-a movement in the direction of conveyance is imparted thereto in the rhythm of the reciprocating movement of said reciprocatable belt roller.

6. Apparatus according to claim 5 wherein said actuating linkage comprises a pivotally mounted double lever which has its first ends pivotally connected to a respective side of the comb-like folding plate, while its second ends are free; spring means for urging the lever towards a position in which the folding plate is in a retracted rest position, the'lever being pivotally mounted at its pivot point in a bearing which is movable with said reciprocatable belt roller; and adjustable stop means arranged in the path of movement of said free ends of the lever, in the region of the forward end of the movement of said reciprocatable belt roller, the stop means co-operating with the lever during the forward movement of the pivot point of the lever until the one stroke movement of the reciprocating motion of said belt roller is completely terminated, whereby the double lever and thus the folding plate are moved in the direction of movement of said reciprocatable belt roller, overtaking the latter, into a forward working position against the force of said spring means.

7. Apparatus according to claim 2 wherein said conveyor means is in the form of a double-belt conveyor having an upper belt guided in the region of its entry end by means of two guide rollers such that a wedgeshaped entry nip is produced, and wherein a further roller is disposed on the inside of the belt run (nip run) spanning across the entry nip, which further roller is movable transversely relative to the nip run and which can be pressed into and removed again from the nip run in the working rhythm of the machine, whereby in operation the nip run is opened and closed in the rhythm of the machine.

8. Apparatus according to claim 7'wherein the upper belts of the double-belt conveyor and the conveyor means are each in the form of astrand belt, the strands of both upper belts are guided at the adjacent ends of the upper belts by means of band pulleys with a common centre, and wherein of the double-belt conveyor only the front roller of the lower belt carries out said reciprocating movement.

9. Apparatus according to claim 2 wherein said conveyor means is in the form of a double-belt conveyor having an upper belt passing in the region of the entry end over two guide rollers such as to form a wedgeshaped entry nip, and wherein a roller is arranged adjacent the conveyor section formed by the upper belt jointly with the lower belt, the roller being so arranged that it can be resiliently flexibly pressed outwardly into the two adjoining runs of said upper belt.

10. Apparatus according to claim 9 wherein the upper belts of the double-belt conveyor and the conveyor means are each in the form of a strand belt, the strands of both upper belts are guided at the adjacent ends of the upper belts by means of band pulleys with acommon centre, and wherein of the double-belt conveyor only the front roller of the lower belt carries out said reciprocating movement.

11. Apparatus according to claim 2 wherein said lower belt is in the form of a strand belt and wherein said folding plate means is of a ladder-like construction with an elongate continuous folding bar and supported at a position lying within the volume enclosed by the lower conveyor belt of said double-belt conveyor, the

beyond the reciprocatable belt rollerv 

1. A method of making a sack or bag comprising a single-ply or multi-ply outer sack, preferably of paper, and an insert sack, preferably of plastics film, which projects out of the outer sack at the filling end for filling, wherein a web of material comprising one or more transversely displaced plies for the outer sack is moved continuously at a given speed, and the insert sack material of a conveyor length corresponding to the insert sack length is advanced more rapidly approximately by the amount intended in the finished sack to projeCt out of the outer sack, and applied to the web of outer sack material, wherein the web of outer sack material is divided by transverse perforations into given outer sack lengths which are still attached to each other, while portions corresponding to the insert sack length are cut off from the web of insert sack material, and attached at one end by means of glue to the web of outer sack material in such a way that said cut edges are flush with the transverse perforations or are at a given spacing therefrom, whereupon the web of outer sack material is made into a tubular shape, thereby surrounding the insert sack portions secured thereto, and singled off into tube portions by tearing the transverse perforations, which tube portions are delivered to a bottom-making or bottom-closing machine, wherein the sack tube portions are formed with the sack filling end leading and the insert sack portions are folded over through 180* at their leading end by the amount intended in the finished sack to project out of the outer sack, and subsequently secured at their trailing end by means of adhesive to the web of outer sack material so that the fold edge of the insert sack portion, which fold edge is formed by said folding-over step, is substantially flush with the transverse perforations in the web of outer sack material.
 2. Apparatus comprising first means for forming single-ply or multi-ply tubes for the outer sacks; second means for advancing and transversely cutting a simple flat or tubular web of material for the insert sacks; a tube-forming apparatus for forming the webs of the outer and insert sacks into a tube; a transverse perforating apparatus arranged upstream of the tube-forming apparatus, for transversely perforating said outer sack web; a glueing mechanism for applying glue to said outer sack web, arranged upstream of the tube-forming apparatus; a tearing-off apparatus arranged downstream of said tube-forming apparatus; an apparatus arranged downstream of said second means for feeding the portions which are cut off from the simple flat or tubular web of material for the insert sacks; and a conveyor means which in operation moves at the speed of conveyance of said outer sack web and which lays the portions of insert sack material onto the outer sack web, the arrangement of the conveyor means being such that the portions of insert sack material are laid onto the web of outer sack material along the section of the latter which extends between said transverse perforating apparatus or glueing mechanism and said tube-forming apparatus; wherein a double-belt conveyor comprising an upper conveyor belt and a lower conveyor belt is disposed between said second means and said conveyor means, which double-belt conveyor in operation moves at a higher speed than the conveyor means, and wherein at least one belt roller of the pair of belt rollers at the end of the double-belt conveyor at which said insert sack portions are transferred to the conveyor means is reciprocatable in the direction of conveyance of the portions of insert sack material in the rhythm of the machine, with tensioning rollers engaging the outer run for maintaining the tension in the belt, and wherein a folding plate means is provided which is also reciprocatable and which in the foremost position extends with its folding edge into the entry nip of said conveyor means along a transverse line lying in the region of the leading end, for introducing an insert sack portion into the converging entry nip of said conveyor means, and prematurely releasing the trailing end.
 3. Apparatus according to claim 2 wherein the folding plate means comprises a folding plate supported on the lower belt of the double-belt conveyor so as to be movable between an upwardly directed working position and a downward inoperative position.
 4. Apparatus according to claim 2 wherein the lower conveyor belt of the double-belt conveyor comprises a plurality of stands and the folding plate means comprises a folding plate of a comb-like conStruction supported at a position lying in the interior of the space enclosed by the lower conveyor belt of the double-belt conveyor, the comb-like fingers projecting between the individual strands of the conveyor belt and being movable to a position in which they extend beyond the reciprocatable belt roller.
 5. Apparatus according to claim 4 wherein the comb-like folding plate is pivotally connected at its rearward end to an actuating linkage by way of which a movement in the direction of conveyance is imparted thereto in the rhythm of the reciprocating movement of said reciprocatable belt roller.
 6. Apparatus according to claim 5 wherein said actuating linkage comprises a pivotally mounted double lever which has its first ends pivotally connected to a respective side of the comb-like folding plate, while its second ends are free; spring means for urging the lever towards a position in which the folding plate is in a retracted rest position, the lever being pivotally mounted at its pivot point in a bearing which is movable with said reciprocatable belt roller; and adjustable stop means arranged in the path of movement of said free ends of the lever, in the region of the forward end of the movement of said reciprocatable belt roller, the stop means co-operating with the lever during the forward movement of the pivot point of the lever until the one stroke movement of the reciprocating motion of said belt roller is completely terminated, whereby the double lever and thus the folding plate are moved in the direction of movement of said reciprocatable belt roller, overtaking the latter, into a forward working position against the force of said spring means.
 7. Apparatus according to claim 2 wherein said conveyor means is in the form of a double-belt conveyor having an upper belt guided in the region of its entry end by means of two guide rollers such that a wedge-shaped entry nip is produced, and wherein a further roller is disposed on the inside of the belt run (nip run) spanning across the entry nip, which further roller is movable transversely relative to the nip run and which can be pressed into and removed again from the nip run in the working rhythm of the machine, whereby in operation the nip run is opened and closed in the rhythm of the machine.
 8. Apparatus according to claim 7 wherein the upper belts of the double-belt conveyor and the conveyor means are each in the form of a strand belt, the strands of both upper belts are guided at the adjacent ends of the upper belts by means of band pulleys with a common centre, and wherein of the double-belt conveyor only the front roller of the lower belt carries out said reciprocating movement.
 9. Apparatus according to claim 2 wherein said conveyor means is in the form of a double-belt conveyor having an upper belt passing in the region of the entry end over two guide rollers such as to form a wedge-shaped entry nip, and wherein a roller is arranged adjacent the conveyor section formed by the upper belt jointly with the lower belt, the roller being so arranged that it can be resiliently flexibly pressed outwardly into the two adjoining runs of said upper belt.
 10. Apparatus according to claim 9 wherein the upper belts of the double-belt conveyor and the conveyor means are each in the form of a strand belt, the strands of both upper belts are guided at the adjacent ends of the upper belts by means of band pulleys with a common centre, and wherein of the double-belt conveyor only the front roller of the lower belt carries out said reciprocating movement.
 11. Apparatus according to claim 2 wherein said lower belt is in the form of a strand belt and wherein said folding plate means is of a ladder-like construction with an elongate continuous folding bar and supported at a position lying within the volume enclosed by the lower conveyor belt of said double-belt conveyor, the rungs of the ladder-like construction projecting between the individual strands of said lower belt, movably beyond the reciprocatable belt roller. 